Added BUILD flags to provision for building the kernel with non-upstream patches (#12428)

* Added ENV vars for non-upstream patches

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

* Made MLNX_PATCH_LOC an absolute path

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

* Added non-upstream-patches dir

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

* Update README.md

* Addressed comments

* Env vars updated

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

* Readme updated

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

Signed-off-by: Vivek Reddy <vkarri@nvidia.com>

platform/mellanox/non-upstream-patches/README.md

@@ -0,0 +1,31 @@
+## Mellanox non-upstream linux kernel patches ##
+
+To include non-upstream patches into the sonic-linux image during build time, this folder must contain a patch archive.
+
+### Structure of the patch archive
+
+  1. It should contain a file named series. series should provide an order in which the patches have to be applied
+  ```
+  admin@build-server:/sonic-buildimage/src/sonic-linux-kernel$ cat linux-5.10.103/non_upstream_patches/series
+  mlx5-Refactor-module-EEPROM-query.patch
+  mlx5-Implement-get_module_eeprom_by_page.patch
+  mlx5-Add-support-for-DSFP-module-EEPROM-dumps.patch
+  ```
+  2. All the patches should be present in the same folder where series resides.
+  3. Developers should make sure patches apply cleanly over the existing patches present in the src/sonic-linux-kernel .
+  4. Name of the tarball should match with the one specified under EXTERNAL_KERNEL_PATCH_TAR
+
+#### Example
+```
+admin@build-server:/sonic-buildimage/platform/mellanox/non-upstream-patches$ tar -tf patches.tar.gz
+./
+./mlx5-Implement-get_module_eeprom_by_page.patch
+./mlx5-Add-support-for-DSFP-module-EEPROM-dumps.patch
+./series
+./mlx5-Refactor-module-EEPROM-query.patch
+```
+
+### Include the archive while building sonic linux kernel
+
+Set `INCLUDE_EXTERNAL_PATCH_TAR=y` using `SONIC_OVERRIDE_BUILD_VARS` to include these changes before building the kernel.
+- Eg: `NOJESSIE=1 NOSTRETCH=1 NOBUSTER=1 make SONIC_OVERRIDE_BUILD_VARS=' INCLUDE_EXTERNAL_PATCH_TAR=y ' target/debs/bullseye/linux-headers-5.10.0-12-2-common_5.10.103-1_all.deb`

platform/mellanox/rules.mk

@@ -51,4 +51,7 @@ $(DOCKER_PLATFORM_MONITOR)_DEPENDS += $(APPLIBS) $(SX_COMPLIB) $(SXD_LIBS) $(SX_
 # Force the target bootloader for mellanox platforms to grub regardless of arch
 TARGET_BOOTLOADER = grub
 
+# location for the platform specific external kernel patches tarball
+override EXTERNAL_KERNEL_PATCH_TAR := $(BUILD_WORKDIR)/$(PLATFORM_PATH)/non-upstream-patches/patches.tar.gz
+
 export SONIC_BUFFER_MODEL=dynamic

rules/linux-kernel.mk

@@ -9,7 +9,17 @@ ifeq ($(CONFIGURED_ARCH), armhf)
 KVERSION = $(KVERSION_SHORT)-armmp
 endif
 
+# Place an URL here to .tar.gz file if you want to include those patches
+EXTERNAL_KERNEL_PATCH_URL =
+# Set y to include non upstream patches tarball provided by the corresponding platform
+INCLUDE_EXTERNAL_PATCH_TAR = n
+# platforms should override this and provide an absolute path to the tarball
+EXTERNAL_KERNEL_PATCH_TAR =
+
 export KVERSION_SHORT KVERSION KERNEL_VERSION KERNEL_SUBVERSION
+export EXTERNAL_KERNEL_PATCH_URL
+export INCLUDE_EXTERNAL_PATCH_TAR
+export EXTERNAL_KERNEL_PATCH_TAR
 
 LINUX_HEADERS_COMMON = linux-headers-$(KVERSION_SHORT)-common_$(KERNEL_VERSION)-$(KERNEL_SUBVERSION)_all.deb
 $(LINUX_HEADERS_COMMON)_SRC_PATH = $(SRC_PATH)/sonic-linux-kernel

slave.mk

@@ -43,7 +43,8 @@ BULLSEYE_DEBS_PATH = $(TARGET_PATH)/debs/bullseye
 BULLSEYE_FILES_PATH = $(TARGET_PATH)/files/bullseye
 DBG_IMAGE_MARK = dbg
 DBG_SRC_ARCHIVE_FILE = $(TARGET_PATH)/sonic_src.tar.gz
-DPKG_ADMINDIR_PATH = /sonic/dpkg
+BUILD_WORKDIR = /sonic
+DPKG_ADMINDIR_PATH = $(BUILD_WORKDIR)/dpkg
 
 CONFIGURED_PLATFORM := $(shell [ -f .platform ] && cat .platform || echo generic)
 PLATFORM_PATH = platform/$(CONFIGURED_PLATFORM)
@@ -84,6 +85,7 @@ export MULTIARCH_QEMU_ENVIRON
 export DOCKER_BASE_ARCH
 export CROSS_BUILD_ENVIRON
 export BLDENV
+export BUILD_WORKDIR
 
 ###############################################################################
 ## Utility rules